WebDyne versions from 2.014 before 3.022 for Perl issue session cookies without the Secure, HttpOnly and SameSite attributes. WebDyne::Session sets its session cookie with only a name, value and path. Browsers then send the session ID over plain HTTP and with cross-site requests, and expose it to page scripts. A network attacker or an injected script can steal the session, and another site can make requests that carry it.